Friction retard feeder with improved sheet separation

ABSTRACT

A substrate feeding apparatus and a printing machine is provided herein for feeding substrates from a substrate stack having a nudger roll being selectively movable between a first position and a second position. In the first position, the nudger roll is in contiguous contact with a first substrate of the substrate stack for advancing the first substrate from the substrate stack. The first substrate having a lead edge and a trail edge, with the lead edge leading in a direction of advancement. In the second position, the nudger roll is not in contiguous contact with the substrate stack or the first substrate. A feed roll for further advancing the first substrate in the direction of advancement. A retard member forming a nip with the feed roll. The retard member is used for separating the first substrate from an adjacent second substrate. A guide baffle extending between the substrate stack and the nip, with the guide baffle configured to contact, and to guide, the first substrate as it advances in the direction of advancement from the nudger roll to the nip. The guide baffle provides an angular change in direction to the first substrate as the first substrate advances from the substrate stack to the nip. The guide baffle is configured such that as the lead edge of the first substrate enters the nip, the first substrate has portions thereof spaced from the guide baffle, with the spaced portions sagging towards the guide baffle to provide the first substrate with a concave profile. The nudger roll moves from the first position to the second position after the lead edge of the first substrate enters the nip.

TECHNICAL FIELD

This disclosure generally relates to substrate (paper) feeders. It moreparticularly concerns a friction retard feeder that improves sheetseparation.

BACKGROUND

Digital Printing using a variety of marking technologies such as:Electrophotographic, Liquid Ink Jet, Solid Ink Jet, is a well-known,commonly used method of copying or printing documents. As the marketplace moves away from only Black and White documents and includes morecolor images, the substrate media used to enhance color images employ asmoother surface finish or surface coatings. Composite substratesconsisting of cellulous and polymer layers or synthetic substrates arebecoming more common. When composite substrates and coated substratesare used, the probability that a substrate feeding apparatus will pullboth a first substrate and an adjacent second substrate increases.

Marking machines typically include one or more substrate feedingsystems. For example, the substrate feeding system might move paper froman input tray to a transfer station. Input trays used in lower costprinters typically employ a friction retard feed mechanism and apivoting elevator plate to raise the substrate stack up to the feedingapparatus as substrates are removed from the substrate stack. Frictionretard feeding mechanisms deflect the first substrate in the directionof the adjacent second substrate, which increases the face-to-facecontact force between the first and second substrates. The face-to-facecontact forces can drag the adjacent second substrate into the feedingmechanism with the first substrate. These contact forces betweencomposite and coated substrates can be twenty times greater thanuncoated substrates, resulting in composite substrates and coatedsubstrates being multi-fed more frequently than uncoated substratesbecause of the increased face-to-face contact forces between the firstsubstrate and the adjacent second substrate.

While prior art substrate feeding systems have been very successful,there exists a need for an improved substrate feeding system for coatedand synthetic media characterized by fewer multiple sheet feedings.

SUMMARY

According to aspects illustrated herein, there is provided a substratefeeding apparatus for feeding substrates from a substrate stack. Thesubstrate feeding apparatus includes a nudger roll being selectivelymovable between a first position and a second position. In the firstposition, the nudger roll is in contiguous contact with a firstsubstrate of the substrate stack for advancing the first substrate fromthe substrate stack. The first substrate having a lead edge and a trailedge, with the lead edge leading in a direction of advancement. In thesecond position, the nudger roll is not in contiguous contact with thesubstrate stack or the first substrate. A feed roll for furtheradvancing the first substrate in the direction of advancement. A retardmember forming a nip with the feed roll. The retard member is used forseparating the first substrate from an adjacent second substrate. Aguide baffle extending between the substrate stack and the nip, with theguide baffle configured to contact and guide, the first substrate as itadvances in the direction of advancement from the nudger roll to thenip. The guide baffle provides an angular change in direction to thefirst substrate as the first substrate advances from the substrate stackto the nip. The guide baffle is configured such that as the lead edge ofthe first substrate enters the nip, the first substrate has portionsthereof spaced from the guide baffle, with the spaced portions saggingtowards the guide baffle to provide the first substrate with a concaveprofile. The nudger roll moves from the first position to the secondposition after the lead edge of the first substrate enters the nip.

According to other aspects illustrated herein, there is provided aprinting machine having a substrate feeder. The printing machineincludes a nudger roll selectively movable between a first position anda second position. In the first position, the nudger roll is incontiguous contact with a first substrate of a substrate stack foradvancing the first substrate from the substrate stack, the firstsubstrate having a lead edge and a trail edge, the lead edge leading ina direction of advancement. In the second position, the nudger rolloverlaps the substrate stack but is not in contiguous contact with thesubstrate stack or the first substrate. A feed roll for furtheradvancing the first substrate in the direction of advancement. A retardmember forming a nip with the feed roll. The retard member being usedfor separating the first substrate from an adjacent second substrate. Aguide baffle extending between the substrate stack and the nip, with theguide baffle configured to contact and guide, the first substrate as itadvances in the direction of advancement from the nudger roll to thenip. The guide baffle is configured such that as the lead edge of thefirst substrate enters the nip, the first substrate has portions thereofspaced from the guide baffle, with the spaced portions sagging towardsthe guide baffle to provide the first substrate with a concave profile.The nudger roll moves from the first position to the second positionafter the lead edge of the first substrate enters the nip.

Additional features and advantages will be readily apparent from thefollowing detailed description, the accompanying drawings and theclaims. It is to be understood, however, that the drawings are designedas an illustration only and not as a definition of the limits of thedisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an apparatus for feeding substrates with an activefriction retard feeder including a guide baffle prior to feeding asubstrate with a nudger roll in a first position.

FIG. 2 illustrates an apparatus for feeding substrates with an activefriction retard feeder including a guide baffle after feeding asubstrate with a nudger roll in a first position.

FIG. 3 illustrates an apparatus for feeding substrates with an activefriction retard feeder including a guide baffle after feeding asubstrate with a nudger roll in a second position.

FIG. 4 illustrates an apparatus for feeding substrates with an activefriction retard feeder including a guide baffle after the substrates areseparated.

FIG. 5 illustrates an apparatus with a partially filled tray ofsubstrates with an active friction retard feeder including a guidebaffle after feeding a substrate with a nudger roll in the firstposition.

FIG. 6 illustrates an apparatus with a partially filled tray ofsubstrates with an active friction retard feeder including a guidebaffle after the substrates are separated and the nudger roll in thesecond position.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

Referring to FIG. 1, an example active friction retard feeder apparatus10 that can be utilized with an Electrophotographic marking machine,such as a printing machine is disclosed.

As used herein, the phrase “printing machine” encompasses any apparatus,such as a digital copier, bookmaking machine, facsimile machine, andmulti-function machine, which performs a printing outputting functionfor any purpose.

As used herein, the terms “substrate” and “substrate stack” include, forexample, one or more of a usually flimsy physical sheet of paper, heavymedia paper, coated papers, transparencies, parchment, film, fabric,plastic, or other suitable physical print media substrate on whichinformation can be reproduced.

As used herein, a “feeding apparatus” encompasses any apparatus forseparating and conveying one or more substrates from a stack ofsubstrates into the substrate conveyance path inside a printing machine.

As used herein, the phrase “feed roll” refers to an article thatadvances the substrates in a “direction of advancement.”

As used herein, the phrase “direction of advancement” refers to adirection the substrates travel in being conveyed from a feedingapparatus to another location.

As used herein, the phrase “nudger roll” refers to an article thatadvances the substrates off the substrate stack in the direction ofadvancement.

As used herein, the phrase “lead edge” refers to the edge of a substratethat first moves in the direction of advancement.

As used herein, the phrase “trail edge” refers to the edge of asubstrate opposite the lead edge.

As used herein, the phrase “contiguous contact” refers to an objectabutting or touching another object. For example, a pen is in contiguouscontact with a piece of paper when the pen is touching the paper.

As used herein, the phrase “retard member” refers to an article thatimpedes movement of the substrates in the direction of advancement.

As used herein, the phrase “face-to-face contact” refers to contactbetween adjacent faces of two substrates.

As used herein the phrase “guide baffle” refers to a device configuredto guide a substrate along a path.

As shown in the example in FIGS. 1-6, the apparatus 10 includes a nudgerroll 12, a feed roll 14, an active retard roll 16, substrate stack 18,and guide baffle 20. The nudger roll 12 has a high friction surface 22that selectively rotates in the direction 24 of advancement. The nudgerroll 12 is movable in a first position 26 and a second position 28 andis located above the substrate stack 18. The substrate stack 18 iscomprised of individual substrates, including a topmost substrate 30 andan adjacent second substrate 32 with an initial amount of face-to-facecontact. In the first position 26, the nudger roll 12 is in contiguouscontact with a topmost substrate 30 and as the nudger roll 12 rotates,the topmost substrate 30 advances in the direction 34 of advancement, asshown in FIG. 2.

The topmost substrate 30, which is also referred to as a firstsubstrate, has a lead edge 36 and a trail edge 38. As the topmostsubstrate 30 contacts the guide baffle 20, the lead edge 36 of thetopmost substrate 30 advances in the direction 34 of advancement and thetopmost substrate 30 is guided to the feed roll 14. The guide baffle 20is operatively connected to a substrate stack 18 and is fixed betweenthe feed roll 14 and the active retard roll 16.

The feed roll 14 has a high friction surface 40 and the active retardroll 16 has a high friction surface 42 that forms a nip 44 in the pathof the topmost substrate 30. The feed roll 14 rotates in the direction46 of advancement and the active retard roll 16 rotates in the direction48 opposite of advancement. The orientation of the feed roll 14 and theactive retard roll 16 is preferably set to align the roll center linesapproximately perpendicular to the guide baffle 20, with the feed rollrotating about a first axis 33 and the guide baffle 20 being oriented tobe generally perpendicular to a reference axis R that intersects the nip44 and the first axis 33.

The guide baffle 20 provides an angular change in direction, representedby angle α, for the topmost substrate 30 as the topmost substrate 30advances from the substrate stack 18 to the feed roll 14. The angle α isdefined between a plane P coinciding with the top of the substrate stack18 in an initial position and the guide baffle 20. As explained below,the substrate stack 18 may be angularly adjusted. The angle α is takenfrom the initial position of the substrate stack 18. The angle α betweenthe guide baffle 20 and the substrate stack 18 may range from about 10degrees to about 70 degrees, more specifically the angle α may rangefrom about 30 degrees and about 40 degrees, and in particular the angleα may be about 35 degrees.

Due to the angular change provided by the guide baffle 20, duringadvancement of the topmost substrate 30, portions of the topmostsubstrate 30 are spaced from the guide baffle 20. The spaced portions ofthe topmost substrate 30 sag towards the guide baffle 20, providing thetopmost substrate 30 with a concave profile 31. As described below, theconcave profile 31 reduces the frictional contact between the substratesand enhances the ability to advance the topmost substrate 30 whileallowing for separation of the second substrate 32. The guide baffle 20preferably passes through the plane P so that the topmost substrate 30,and subsequent substrates, during advancement intersect the guide baffle20 at a location spaced from end 39 of the guide baffle 20. With theguide baffle 20 passing through the plane P, the end 39 is located belowthe plane P. This configuration additionally facilitates the formationof the concave profile 31.

The apparatus 10 is configured to allow the nudger roll 12 to advancethe topmost substrate 30 in the direction 34 of advancement until thelead edge 36 of the topmost substrate 30 enters the nip 44. As shown inFIGS. 2-3, after the topmost substrate 30 enters the nip 44, the nudgerroll 12 moves from the first position 26 to the second position 28. Inthe second position 28, the nudger roll 12 is retracted, such that thenudger roll 12 is not in contiguous contact with the substrate stack 18or the topmost substrate 30, reducing the face-to-face contact forcebetween the topmost substrate 30 and the adjacent second substrate 32from the initial amount of face-to-face contact force between them.

As the topmost substrate 30 advances in the direction 34 of advancement,the active retard roll 16 advances the adjacent second substrate 32 inthe direction 35 opposite of advancement, separating from the topmostsubstrate 30 and forming a separation point 50 between the topmostsubstrate 30 and the adjacent second substrate 32. The concave curvedprofile 31 created by the guide baffle 20 and the opposing motion of thetopmost substrate 30 and the adjacent second substrate 32 caused by thefeed roll 14 and active retard roll 16 acts against the face-to-facecontact forces, enabling the topmost substrate 30 and the adjacentsecond substrate 32 to progressively peel apart by pushing the secondsubstrate 32 towards the baffle 20, while the first substrate 30 isbeing lifted opposite to the baffle 20. Since the nudger roll 12 is inthe second position 28, this peeling separation point 50 between thetopmost substrate 30 and the adjacent second substrate advances, withoutobstruction, from near the lead edge 36 towards the trail edge 38.

FIG. 4 shows the apparatus 10 after the topmost substrate 30 and theadjacent second substrate 32 are separated. After separating, thetopmost substrate 30 continues moving in the direction 34 of advancementtowards another location in the feeding apparatus, and the adjacentsecond substrate 32 continues moving in the direction 35 opposite ofadvancement until the lead edge of the adjacent second substrate 32exits the nip 44. The second substrate 32 then becomes the topmostsubstrate 30 and the process repeats.

The substrate stack 18 may be advanced vertically to continuously feedsubstrates. Alternatively, the substrate stack 18 may be pivotallyadjusted to raise the leading edges of the substrates in further feedingsubstrates. For example, with reference to FIGS. 5 and 6, the substratefeeding apparatus 10 is shown with a substrate tray 60 only partiallyfilled by the substrate stack 18. As the substrate stack 18 reduces inheight, the substrate stack 18 is pivotally adjusted into a position tobe fed by the nudger roll 12 using an elevator plate 62 with a pivotpoint 66 and a lift mechanism 64. The elevator plate 62 has a lead edge68 and a trail edge 70, with the pivot point 66 located adjacent to thetrail edge 70 of the elevator plate 62. The lift mechanism 64 is locatednear the lead edge 68 of the elevator plate 62 and lifts the elevatorplate 62, about the pivot point 66, towards the nudger roll 12, assubstrates are fed from a top portion 72 of the substrate stack 18.

The elevator plate 62 maintains the substrate stack 18 at a constantvertical distance relative to the nip 44 formed by the feed roll 14 andthe retard roll 16. The vertical position of the substrate stack 18relative to the nip 44 is typically measured with a sensor (not shown)that monitors the position of the nudger roll 12 in the first position26 and tracks the topmost substrate 30 as substrates are fed from thesubstrate stack 18. When the first position 26 of the nudger roll 12drops below a predetermined height relative to the nip 44, the liftingapparatus 64 for the elevator plate 62 is enabled to raise the lead edge68 of the elevator plate 62 and the substrate stack 18.

As substrates are removed from the substrate stack 18, an angle ofinclination δ between the elevator plate 62 and the substrate tray 60increases. The increased angle of inclination δ of the substrate stack18 changes the trajectory of the lead edge of the topmost substrate 30of the substrate stack 18 to be directed increasingly above the nip 44.To obtaining the concave profile 31 of the topmost substrate 30 thesubstrate feeder 10 must be configured such that angle β, representingthe difference between the plane P, which coincides with the initialposition of the top of the substrate stack 18, and the current positionof the top of the substrate stack 18, remains less than angle α (angle αbeing constant). Thus, when the apparatus 10 includes an elevator plate62 that changes the slope of the substrate stack 18, angle α ispreferably selected such that angle α remains greater than angle β.

While the above description and FIGS. 1-6 provide an example of anactive retard roll 16, it is readily understood that the broader aspectsof this disclosure are applicable to other types of retard members,including a semi-active retard roll and a retard pad. The advantage ofusing an active retard roll 16 is that the active retard roll 16 drivesthe adjacent second substrate 32 towards the substrate stack 18 and inthe direction 35 opposite of advancement. Use of the semi-active retardroll or the retard pad may reduce the separation gap between the sheets.

It will be appreciated that various of the above-disclosed and otherfeatures and functions, or alternative thereof, may be desirablycombined into many other different systems or applications. Variouspresently unforeseen or unanticipated alternatives, modifications,variations, or improvements therein may be subsequently made by thoseskilled in the art which are also intended to be encompassed by thefollowing claims. In addition, the claims can encompass embodiments inhardware, software, or a combination thereof.

1. A substrate feeding apparatus for feeding substrates from a substratestack comprising: a nudger roll selectively movable between a firstposition and a second position, wherein in said first position, saidnudger roll is in contiguous contact with a first substrate of saidsubstrate stack for advancing said first substrate from the substratestack, said first substrate having a lead edge and a trail edge, saidlead edge leading in a direction of advancement, and wherein, in saidsecond position, said nudger roll is not in contiguous contact with saidsubstrate stack or said first substrate; a feed roll for furtheradvancing said first substrate in the direction of advancement; a retardmember forming a nip with said feed roll, said retard member forseparating said first substrate from an adjacent second substrate; and aguide baffle extending between said substrate stack and said nip, saidguide baffle configured to contact, and guide, said first substrate asit advances in the direction of advancement from said nudger roll tosaid nip, said guide baffle providing an angular change in direction tosaid first substrate as said first substrate advances from saidsubstrate stack to said nip, wherein, said guide baffle being configuredsuch that as said lead edge of said first substrate enters said nip,said first substrate has portions thereof spaced from said guide baffle,said spaced portions sagging towards said guide baffle to provide saidfirst substrate with a concave profile; wherein said nudger roll movesfrom said first position to said second position after the lead edge ofsaid first substrate enters said nip.
 2. The apparatus of claim 1,wherein said retard member is an active retard roll.
 3. The apparatus ofclaim 2, wherein said active retard roll separates said first substratefrom an adjacent second substrate by advancing said adjacent secondsubstrate in a direction opposite of the direction of advancement whilethe feed roll advances said first substrate in the direction ofadvancement.
 4. The apparatus of claim 1, wherein said retard member isa semi-active retard roll.
 5. The apparatus of claim 1, wherein saidretard member is a pad.
 6. The apparatus of claim 1, wherein a firstangle is formed between said guide baffle and said substrate stack, saidfirst angle is about 10 degrees to about 70 degrees.
 7. The apparatus ofclaim 1, wherein a first angle is formed between said guide baffle andsaid substrate stack, said first angle is about 30 degrees to about 40degrees.
 8. The apparatus of claim 1, wherein said guide baffle is fixedbetween said substrate stack and said nip.
 9. The apparatus of claim 1,wherein the orientation of said feed roll and said retard member isrotated to align the roll center lines approximately perpendicular tosaid guide baffle, wherein said feed roll rotates about a first axis andwherein said guide baffle is oriented to be generally perpendicular to areference axis which intersects said nip and said first axis.
 10. Theapparatus of claim 1, wherein a second angle is formed between areference plane coinciding with an initial position of said substratestack and a current position of said substrate stack, said second anglebeing less than said first angle.
 11. The apparatus of claim 1, furthercomprising an elevator plate extending adjacent to said substrate stackwith a pivot point and a lift mechanism, wherein said elevator plate hasa lead ledge and a trail edge, said pivot point being located adjacentto said trail edge of said elevator plate and said lift mechanismconfigured to pivotally adjust said lead edge of said elevator plate toallow said lead edge of said first substrate to contact and align withsaid guide baffle as said first substrate advances from said substratestack to said nip.
 12. A printing machine comprising: a substrate feederincluding: a nudger roll selectively movable between a first positionand a second position, wherein in said first position, said nudger rollis in contiguous contact with a first substrate of a substrate stack foradvancing the first substrate from the substrate stack, said firstsubstrate having a lead edge and a trail edge, said lead edge leading ina direction of advancement, and wherein, in said second position; saidnudger roll overlaps said substrate stack but is not in contiguouscontact with said substrate stack or said first substrate; a feed rollfor further advancing said first substrate in the direction ofadvancement; a retard member forming a nip with said feed roll, saidretard member for separating said first substrate from an adjacentsecond substrate; and a guide baffle extending between said substratestack and said nip, said guide baffle configured to contact, and guide,said first substrate as it advances in the direction of advancement fromsaid nudger roll to said nip, said guide baffle providing an angularchange in direction to said first substrate as said first substrateadvances from said substrate stack to said nip, wherein, said guidebaffle being configured such that as said lead edge of said firstsubstrate enters said nip, said first substrate has portions thereofspaced from said guide baffle, said spaced portions sagging towards saidguide baffle to provide said first substrate with a concave profile;wherein said nudger roll moves from said first position to said secondposition after the lead edge of the first substrate enters the nip. 13.The printing machine of claim 12, wherein said retard member is anactive retard roll, said active retard roll separates said firstsubstrate from an adjacent second substrate by advancing said adjacentsecond substrate in a direction opposite of the direction of advancementwhile the feed roll advances said first substrate in the direction ofadvancement.
 14. The printing machine of claim 12, wherein said retardmember is a semi-active retard roll.
 15. The printing machine of claim12, wherein said retard member is a pad.
 16. The printing machine ofclaim 12, wherein a first angle is formed between said guide baffle andsaid substrate stack, said first angle is about 10 degrees to about 70degrees.
 17. The printing machine of claim 12, wherein a first angle isformed between said guide baffle and said substrate stack, said firstangle is about 30 degrees to about 40 degrees.
 18. The printing machineof claim 12, further comprising an elevator plate extending adjacent tosaid substrate stack with a pivot point and a lift mechanism, whereinsaid elevator plate has a lead ledge and a trail edge, said pivot pointbeing located adjacent to said trail edge of said elevator plate andsaid lift mechanism configured to pivotally adjust said lead edge ofsaid elevator plate to allow said lead edge of said first substrate tocontact and align with said guide baffle as said first substrateadvances from said substrate stack to said nip.
 19. The printing machineof claim 12, wherein the orientation of said feed roll and said retardmember is rotated to align the roll center lines approximatelyperpendicular to said guide baffle, wherein said feed roll rotates abouta first axis and wherein said guide baffle is oriented to be generallyperpendicular to a reference axis which intersects said nip and saidfirst axis.
 20. The printing machine of claim 12, wherein a second angleis formed between a reference plane coinciding with an initial positionof said substrate stack and a current position of said substrate stack,said second angle being less than said first angle.